1. Field of the Invention
The present invention relates to a reflective-transmissive type liquid crystal display device and a method for fabricating the same, and more particularly to a reflective-transmissive type liquid crystal display device and a method for fabricating the same, which can prevent afterimage from generating during a display process caused by ions and impurities remained in an orientation film when forming the orientation film, thereby improving quality of display.
2. Description of the Related Art
Liquid crystal display devices may be fabricated to have a slimmer, smaller and lighter structure regardless of a screen size thereof.
Such liquid crystal display devices are remarkably different from cathode ray tube (CRT) type display devices, in which thickness, volume and weight thereof increase proportional to a size thereof.
Different from the CRT type display devices, the liquid crystal display devices may reduce thickness, volume and weight thereof by filling liquid crystal therein. The liquid crystal has a thickness of few micrometers (μm), but controls quality of light.
The liquid crystal display devices further require light to display image information, since the liquid crystal does not generate light itself, but only controls quantity of light.
The liquid crystal display devices are classified as reflective type liquid crystal display devices, transmissive type liquid crystal display devices and reflective-transmissive type liquid crystal display devices depending on kinds of light sources as used.
The reflective type liquid crystal display devices display image information using external light, such as solar light, indoor illuminating light and outdoor illuminating light. The reflective type liquid crystal display devices display the image information with low power consumption because these devices consume power only in controlling the liquid crystal.
However, the reflective type liquid crystal display devices may not display image information if the external light is not provided or insufficiently provided thereto.
The transmissive type liquid crystal display devices obtain artificial light by using, for example, a cold cathode fluorescent type lamp (CCFL), and display image information by passing the artificial light through the liquid crystal. Therefore, the transmissive type liquid crystal display devices may display image information under any environmental conditions regardless of the external light.
However, the transmissive type liquid crystal display devices display image information at high power consumption because these devices generate light by consuming electric energy even when the external light is sufficiently provided thereto.
The reflective-transmissive type liquid crystal display devices have advantages of the reflective type and transmissive type liquid crystal display devices. The reflective-transmissive type liquid crystal display devices display image information using the artificial light where the external light is not provided or insufficiently provided. In addition, the reflective-transmissive type liquid crystal display devices display image information using the external light where the external light is sufficiently provided.
Accordingly, the reflective-transmissive type liquid crystal display devices may remarkably reduce power consumption as compared with the transmissive type liquid crystal display devices, while displaying image information regardless of environmental conditions thereof.
FIG. 1 is a sectional view showing a conventional reflective-transmissive type liquid crystal display device.
Referring to FIG. 1, a conventional reflective-transmissive type liquid crystal display device 100 includes a TFT (Thin Film Transistor) substrate 10, a color filter substrate 20 and a liquid crystal 30.
In addition, the reflective-transmissive type liquid crystal display device 100 includes a driving module (not shown), which generates a driving signal to control the liquid crystal 30 to display an image.
The TFT substrate 10 includes a transparent substrate 11, a thin film transistor 12, an organic insulation layer 13, a pixel electrode 14 and an orientation film 15.
The thin film transistor 12 is arranged on the transparent substrate 11 in a matrix configuration. The thin film transistor 12 includes a gate electrode 12a, a channel layer 12b, a source electrode 12c and a drain electrode 12d. 
The organic insulation layer 13 is disposed on an upper surface of the transparent substrate 11 in order to insulate the thin film transistor 12. The organic insulation layer 13 is provided with a contact hole 13a for exposing the drain electrode 12d of the thin film transistor 12.
The pixel electrode 14 is disposed on an upper surface of the organic insulation layer 13. The pixel electrode 14 includes a transparent electrode 14a and a reflective electrode 14b. 
The transparent electrode 14a is formed by patterning indium tin oxide (ITO) or indium zinc oxide (IZO), having high light transmittance and conductivity, on the organic insulation layer 13.
The transparent electrode 14a is connected to the drain electrode 12d of the thin film transistor 12 through the contact hole 13a of the organic insulation layer 13. First light (that is generated from an under portion of the transparent substrate 11) passes through the transparent electrode 14a. That is, the first light passes through the transparent electrode 14a to display image information when external light is not provided or insufficiently provided to the device 100.
The reflective electrode 14b is disposed on an upper surface of the transparent electrode 14a. The reflective electrode 14b includes a metal having high light reflectivity. The reflective electrode 14b reflects second light having a direction opposite to a direction of the first light in order to display image information.
An opening window 14c is disposed at a center of the reflective electrode 14b to partially expose the transparent electrode 14a, so the reflective electrode 14b has an area smaller than that of the transparent electrode 14a. 
The first light passes through the opening window 14c to display image information in a dark place where the external light is insufficiently provided.
The orientation film 15 is disposed over the entire area of an upper surface of the transparent substrate 11 with a shallow thickness after the pixel electrode 14 has been formed on the transparent substrate 11.
The orientation film 15 prevents the liquid crystal 30 from being randomly aligned. That is, the liquid crystal 30 is aligned in a predetermined pattern by the orientation film 15. To this end, an orientation groove (15a in FIGS. 2 to 4) is disposed on an upper surface of the orientation film 15.
The orientation groove 15a is regularly disposed on the orientation film 15 through a rubbing process. In order to form the orientation groove 15a, a rubbing fabric having piles rotates and forwardly moves while making contact with the orientation film 15.
The color filter substrate 20 is coupled to the TFT substrate 10 after the orientation film 15 has been formed on the TFT substrate 10.
The color filter substrate 20 includes a transparent substrate 21, a color filter 22, and a common electrode 23. The color filter 22 is disposed on the transparent substrate 21 in opposition to the pixel electrode 14 disposed on the TFT substrate 10.
The common electrode 23 is disposed on an entire surface of the color filter 22 such that the color filter 22 covers the transparent substrate 21.
The liquid crystal 30 is interposed between the color filter substrate 20 and the TFT substrate 10.
However, the above-mentioned conventional reflective-transmissive type liquid crystal display device 100 generates an afterimage during a display process, thereby deteriorating quality of image information. The afterimage is generated due to an orientation of the pixel electrode 14 and the orientation groove 15a. 
FIG. 2 is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 1 o'clock direction, FIG. 3 is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 11 o'clock direction, and FIG. 4 is a schematic view of the conventional reflective-transmissive type liquid crystal display device having an orientation groove oriented in the 6 o'clock direction.
Referring to FIG. 2, when the orientation groove 15a is oriented in the 1 o'clock direction, the liquid crystal 30 is stably aligned without causing any problems at the reflective electrode 14b of the pixel electrode 14. However, a response speed of the liquid crystal 30 is deteriorated at an inner part of the opening window 14c, so that the afterimage is generated in the inner part of the opening window 14c. In FIG. 2, an afterimage region is shown as “A”. The afterimage region A is opposite to the orientation groove 15a. 
Referring to FIG. 3, when the orientation groove 15a is oriented in the 11 o'clock direction, the liquid crystal 30 is stably aligned without causing any problems at the reflective electrode 14b of the pixel electrode 14. However, the response speed of the liquid crystal 30 is also deteriorated at the inner part of the opening window 14c, so that the afterimage is generated in the inner part of the opening window 14c. In FIG. 3, the afterimage region is shown as “B”. The afterimage region B is opposite to the orientation groove 15a. 
Referring to FIG. 4, when the orientation groove 15a is oriented in the 6 o'clock direction, the liquid crystal 30 is stably aligned without causing any problems at the reflective electrode 14b of the pixel electrode 14. However, the response speed of the liquid crystal 30 is also deteriorated at the inner part of the opening window 14c, so that the afterimage is generated in the inner part of the opening window 14c. In FIG. 4, the afterimage region is shown as “C”. The afterimage region C is opposite to the orientation groove 15a. 
Referring to FIGS. 2 to 4, the afterimage regions A, B and C are commonly related to a position of the opening window 14c disposed in the reflective electrode 14b and a rubbing direction.
When performing a rubbing process, the ions or impurities attached to a pile of a rubbing fabric are outwardly moved due to a rotation of the rubbing fabric. The ions or impurities are not discharged out of the pixel electrode 14, but stacked at a boundary between the transparent electrode 14a and the reflective electrode 14b because a step portion is disposed at the boundary between the transparent electrode 14a and the reflective electrode 14b. 
As a result, the response speed of the liquid crystal 30 shown in FIG. 1 is deteriorated due to the impurities or ions stacked at the boundary between the transparent electrode 14a and the reflective electrode 14b. If the response speed of the liquid crystal 30 is slower than a standard speed, the afterimage is generated, thereby deteriorating quality of image information.